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There are three concurrency control strategies available: All of our tutorials thus far have used the default concurrency resolution strategy - namely, we've let the last write win.
In this tutorial we'll examine how to implement optimistic concurrency control.
For example, if a user locks a record for editing and then leaves for the day before unlocking it, no other user will be able to update that record until the original user returns and completes his update.
Therefore, in situations where pessimistic concurrency is used, there's typically a timeout that, if reached, cancels the lock.
To have this Table Adapter employ optimistic concurrency control, simply check the "Use optimistic concurrency" checkbox. Get Product By Product ID(original_product ID) If products.
Figure 6: Enable Optimistic Concurrency Control by Checking the "Use optimistic concurrency" Check Box (Click to view full-size image) Lastly, indicate that the Table Adapter should use the data access patterns that both fill a Data Table and return a Data Table; also indicate that the DB direct methods should be created. Count = 0 Then ' no matching record found, return false Return False End If Dim product As _ Northwind Optimistic Concurrency.
Jisun changes the product name to "Chai Tea" and clicks the Update button. At this point in time, the database has the values "Chai Tea," the category Beverages, the supplier Exotic Liquids, and so on for this particular product.
Both click the Edit button in the Grid View around the same time.Bromberg's Optmistic Concurrency Updating Logic for a brief look at a number of options). NET Typed Data Set provides one implementation that can be configured with just the tick of a checkbox.Enabling optimistic concurrency for a Table Adapter in the Typed Data Set augments the Table Adapter's statement, for example, updates the name and price of a product only if the current database values are equal to the values that were originally retrieved when updating the record in the Grid View.Note We won't look at pessimistic concurrency examples in this tutorial series.
Pessimistic concurrency is rarely used because such locks, if not properly relinquished, can prevent other users from updating data.Figure 1: When Two Users Simultaneously Update a Record There s Potential for One User 's Changes to Overwrite the Other 's (Click to view full-size image) Similarly, when two users are visiting a page, one user might be in the midst of updating a record when it is deleted by another user.